John DeWolf, senior vice president of Howard Hughes Corp., which owns the building, said the company would work with the USPS if they want to remain in the building.

"There ought to be a post office in downtown Columbia," DeWolf said. "We are at the mercy of them right now."

The post office's lease expires May 31, 2014.

If an agreement between the USPS and Howard Hughes can not be reached, the post office could become the latest tenant to leave the building, located across from the Columbia mall on Little Patuxent Parkway.

Earlier this year, Enterprise Community Partners, a nonprofit founded by Jim Rouse, moved into four floors at 70 Corporate Center, the former home of the Ryland Group.

The Ryland Group building, as it is known, was acquired by Howard Hughes in August 2012.

According to a tenant listing at the American City Building, the only occupants are four first-floor tenants — the post office, the Columbia Archives, the Artists' Gallery and Lakeside Deli & Cafe — and one tenant on the third floor.

DeWolf said Howard Hughes has long-term plans to renovate the building, which would include constructing a new "skin" or exterior.

"It's an old building that needs substantial reinvestment," DeWolf said.

DeWolf said a renovation would only take place after Howard Hughes landed a "signature" tenant for the space, which he said would occupy most, if not all, of the upstairs space for the nine-story building.

"We have been hard at work but lightning has to strike a little," he said.

DeWolf said Howard Hughes has explored demolishing the building and constructing residential units, but decided against it.

Currently, Howard Hughes is in the process of redeveloping the former Rouse Co. building, which neighbors the American City Building, into a Whole Foods. Howard Hughes and the Columbia Association have signed an 11-year lease for the basement of the building. CA plans to build a fitness club in the space.

Officials from Columbia landowner Howard Hughes Corp. say the vision for the 93-acre crescent property is to create a downtown employment center that also will include a 300-room hotel, a 50,000-square-foot conference center and streetscape retail.

Preliminary plans to build a hotel, 400 residential units, retail and office space on approximately 23 acres of land on downtown Columbia's crescent property will be revealed at a pre-submission community meeting.

For the first time ever, the Sweetlife Festival — now entering its sixth year — will take over Merriweather Post Pavilion for two days, May 30-31. The expansion, along with the lineup, was announced on the Sweetlife website today.